I had the same issue; it is not the mags; aftermarket mags had the same issues, as did they for some other members here and on the other forum. The issue is that the slide release is too short to engage either the Norinco mags or aftermarket mags. I solved the problem by tig welding the slide release to build it up, then hand working it. I verifying that it engages the mag follower without interference. Once I'm happy with the fit, I reblue.
I have done this for a number of other members and all have been very happy with the fix. I do the work for the cost of return shipping the mag release. I don't need the whole pistol as I have a pistol here to use for fitting.
If you are interested, send me a message.
Mark
Mark fixed my brother's Norc as well... it was this problem 100%.